My E Class 250 Coupe is just over 7 years old. Have had one wheel refurbished by diamond cutting. Have lived with the finish on 2 of the wheels peeling away due to really poor quality MB alloys. MB admitted quality no good and 'generously' offered me 50% discount on new wheels a few years ago but the cost was exhorbitant. Have now decided to refurbish all 4 with powder coating rather than diamond cutting as this should last longer. I like diamond cut but let's face it after 100 yards down the road you can't tell the difference between diamond cut and powder coating! Car hasn't really missed a beat in it's lifetime, no creaks and is a pleasure to drive, so it's worth getting the wheels looking better and the car seems to be a keeper!